D3D12 Work Graphs released

This is the official release of D3D12 Work Graphs, enabling new types of GPU autonomy, originally available as a preview in 2023.

To start, here’s what Epic sees:

With the proliferation of GPU-driven rendering techniques – such as Nanite in Unreal Engine 5 – the role of the CPU is trending towards primarily resource management and hazard tracking, with only a fraction of time spent generating GPU commands. Prior to D3D12 Work Graphs, it was difficult to perform fine-grained memory management on the GPU, which meant it was practically impossible to support algorithms with dynamic work expansion. Even simple long chains of sequential compute work could result in a significant synchronization and memory overhead.
GPU-driven rendering was accomplished by the CPU having to guess what temporary allocations were needed by the GPU, often over-allocating to the worst case, and using previous frame readback for refinement. Any workloads with dynamic expansion either meant issuing worst case dispatches from the CPU, having the GPU early out of unnecessary work, or non-portable techniques were used, like persistent threads.
With Work Graphs, complex pipelines that are highly variable in terms of overall “shape” can now run efficiently on the GPU, with the scheduler taking care of synchronization and data flow. This is especially important for producer-consumer pipelines, which are very common in rendering algorithms. The programming model also becomes significantly simpler for developers, as complex resource and barrier management code is moved from the application into the Work Graph runtime.
We have been advocating for something like this for a number of years, and it is very exciting to finally see the release of Work Graphs.
— Graham Wihlidal, Epic Games

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If you’re attending GDC 2024 there’s a few opportunities to get a deep dive on the most recent developments with Work Graphs:

• DirectX State of the Union
• AMD’s Future of GPU Programming
• Nanite’s GPU-driven Materials
  • This talk from Graham at Epic has a bit on early observations using Work Graphs

GPU vendor Work Graph blogs:

• AMD
• NVIDIA

Development links:

• Full Work Graphs spec, the blog below is a quicker intro.
• Start now on AMD and NVIDIA GPUs
• Samples
• Use PIX with Work Graphs

The content below is similar to the 2023 preview blog, mostly a refresh. See Notable changes since 2023 preview below.

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Contents​

• Introduction to work graphs
  • Basis
  • Characteristics
  • Analysis
  • Scenarios summary
• Specification <—— the docs
• Node types
  • Broadcasting launch
  • Coalescing launch
  • Thread launch
• Other features
  • Adding nodes to existing work graphs
  • New way to define graphics and compute pipelines
• Condensed programming guide
  • Drivers and other prerequisites <—— get running on AMD and NVIDIA
  • Authoring shaders
  • Creating a work graph on a device
  • Dispatching a work graph in a commandlist
• Samples
  • D3D12HelloWorkGraphs
  • D3D12WorkGraphsSandbox
  • D3D12HelloGenericPrograms
• PIX
• Notable changes since 2023 preview